Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
1999-11-26
2001-11-13
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S054000, C477S107000, C477S115000
Reexamination Certificate
active
06317670
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention relates to a control unit and a control method of an automatic transmission used for a power transmission mechanism which converts a drive force of an engine in an automotive vehicle by means of the automatic transmission so as to transmit to an axle.
As the control unit of the automatic transmission in accordance with the prior art, for example, as described in Japanese Patent Unexamined Publication No. 6-147304, there has been known a method of performing a travelling load estimation and an incline estimation on the basis of a torque estimation so as to optimally control the automatic transmission. In this method, it is structured such as to determine an input torque of a torque converter by utilizing a characteristic of the torque converter when a velocity ratio (that is, a slip ratio) of the torque converter is equal to or less than a predetermined value, determine an engine torque by utilizing a torque characteristic of the engine in an area over the value, determine both calculated values, that is, calculate the input torque and the engine torque of the torque converter substantially at the same time when both are switched (that is, at a time of switching from a torque converter characteristic method to an engine torque characteristic method), calculate a difference between the both as a torque component of auxiliary machines (comprising loads of an air conditioner, a head light, a power steering and the like), and subtracting the torque component of the auxiliary machines from the calculated engine torque so as to determine an input shaft torque. Then, by multiplying this torque of the torque converter input shaft by a torque ratio obtained on the basis of another torque converter characteristic (a torque ratio characteristic), an output shaft torque in the torque converter is calculated.
However, since the torque converter characteristic (a characteristic of coefficient of a pump capacity and a torque ratio characteristic) uses a characteristic of an oil temperature (80° C.) at which the engine and the automatic transmission are generally used, the characteristic of the torque converter changes under a state that an oil temperature before the engine is started is low and a state that an oil temperature becomes very high due to an overload operation, so that an error in calculating the torque of the torque converter output shaft is increased.
Then, for example, as described in Japanese Patent Unexamined Publication No. 8-121581, it has been known to correct the torque of the torque converter output shaft in accordance with the oil temperature of the automatic transmission.
However, in accordance with researches performed by the inventors of the present invention, it is not always sufficient to correct the torque of the torque converter output shaft on the basis of the oil temperature of the automatic transmission, and it becomes apparent there is a problem that the error of the calculated torque of the torque converter output shaft is still large.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a control unit and a control method of an automatic transmission which can accurately estimate an output shaft torque in a torque converter with a further little error.
(1) In order to achieve the object mentioned above, in accordance with the present invention, there is provided a control unit of an automatic transmission having torque estimating means for estimating an output shaft torque in a torque converter with using a characteristic of the torque converter and controlling the automatic transmission by using the torque converter output shaft torque estimated by the torque estimating means, wherein the torque estimating means corrects at least one of a pump capacity characteristic and a torque ratio characteristic of the torque converter by using an oil temperature of the automatic transmission and at least one of parameters expressing an operating state, the parameters comprising a torque of an input of the torque converter, an input shaft speed in the torque converter, a relative velocity difference between the input shaft and the output shaft in the torque converter, a velocity change component of the input shaft in the torque converter, a velocity change component of the output shaft in the torque converter, a relative velocity change component of the input shaft and the output shaft in the torque converter, a driving force of the input shaft in the torque converter, a driving force of the output shaft in the torque converter, and a ratio of the driving forces between the input shaft and the output shaft in the torque converter, thereby estimating the torque converter output shaft torque.
In accordance with the structure mentioned above, since the torque converter output shaft torque is calculated by further using the parameters expressing the operating state other than the oil temperature of the automatic transmission, the error of the torque converter output shaft torque can be further reduced and it is possible to accurately estimate the torque converter output shaft torque.
(2) In the control unit of the automatic transmission defined in the item (1) mentioned above, preferably, the torque estimating means calculates the engine torque Te on the basis of an engine speed Ne and a throttle valve opening TVO.
(3) In the control unit of the automatic transmission defined in the item (1) mentioned above, preferably, the torque estimating means calculates a difference of a torque converter relative speed &Dgr;N on the basis of a difference between an engine speed Ne and a turbine speed Nt.
(4) In the control unit of the automatic transmission defined in the item (1) mentioned above, preferably, the torque estimating means coverts an engine speed Ne into an angular velocity, calculates a velocity change component &Dgr;Ve of the engine speed Ne by taking a time differentiation, calculates a velocity change component &Dgr;Vt of the turbine speed Nt and calculates a torque converter relative velocity ratio &Dgr;V on the basis of a difference between the velocity change component &Dgr;Ve of the engine speed Ne and the velocity change component &Dgr;Vt of the turbine speed Nt.
(5) In the control unit of the automatic transmission defined in the item (1) mentioned above, preferably, the torque estimating means calculates an engine torque Te on the basis of an engine speed Ne and a throttle valve opening TVO, calculates a driving force Le of a torque converter input shaft by multiplying the calculated engine torque Te by an angular velocity &ohgr;e of the torque converter input shaft, calculates a driving force Lt of a torque converter output shaft by multiplying a pump capacity coefficient Cp0 and a torque ratio t0 calculated on the basis of a velocity ratio e between the engine speed and the number of rotation in the torque converter by a square value Ne
2
of the engine speed and an angular velocity &ohgr;t of the torque converter output shaft, and calculates a torque converter driving force ratio R on the basis of a ratio between a driving force Le of the torque converter input shaft and a driving force Lt of the torque converter output shaft.
(6) In order to achieve the object mentioned above, in accordance with the present invention, there is provided a control method of an automatic transmission comprising steps of estimating an output shaft torque in a torque converter with using a characteristic of the torque converter and controlling the automatic transmission by using the estimated torque converter output shaft torque, wherein the improvement comprises a step of correcting at least one of a pump capacity characteristic and a torque ratio characteristic of the torque converter by using an oil temperature of the automatic transmission and at least one of five parameters expressing an operating state, the parameters comprising a torque of an input of the torque converter, an input shaft speed in the torque converter, a relative velocity difference between the input shaft and
Kuroiwa Hiroshi
Minowa Toshimichi
Noda Junichi
Okada Mitsuyoshi
Beaulieu Yonel
Crowell & Moring LLP
Cuchlinski Jr. William A.
Hitachi , Ltd.
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